The invention relates to a roll arrangement comprising a rotatable, preferably flexible roll jacket, a stationary carrier and a multi-part support arrangement which is disposed between the roll jacket and the carrier, with the roll arrangement including sliding shoes which are movable in the radial direction relative to the roll jacket and have support surfaces facing the roll jacket.
Such roll arrangements are for example used for the treatment of paper webs. It is extremely important, in particular in the smoothing of paper webs, that the press force which is exerted onto the paper web by the support arrangements via the roll jacket is uniform over the width of the paper web. Even the smallest differences in the pressing force can lead to relatively large differences with respect to the smoothing effect. In practice this means that the paper web has been smoothed to different degrees over its width after passing through the smoothing zone. Such differences represent deficiencies in quality which can make the paper unmarketable.
A roll arrangement intended for the smoothing of a paper web is known from DE 43 22 876 A1 in which support arrangements are used in the form of sliding shoes which can be pressed against the roll jacket and which are built up from individual sections in the form of beams which follow one another in the running direction. The beams can also be subdivided into sections transverse to the running direction of the web. Use can be made of either a single large pressing element which can act on the entire shoe consisting of individual sections, or of several pressing elements which are associated with the individual sections or portions. The aim of subdividing the sliding shoe into individual sections of portions is to avoid distortion effects which can arise in a one-piece shoe and which impair the smoothing quality, and also to maintain the geometry of the smoothing zone even with changing operating temperatures.
In order to avoid the unavoidable partition gaps between the individual sections or portions leaving tracks in the paper web, provision is made in this known arrangement for the surface of the sliding shoe consisting of individual sections which faces the roll to be covered by a layer which forms the sliding surface and which is weak in bending and can consist of a foil or of a piece of sheet metal.
With such a layer, which in other respects can only be used if no hydrostatic support of the roll jacket is required, it is not however possible to avoid a loss of support at the gaps between the individual sections. A loss of support and oil in the region of the existing gaps which results from the subdivision of the unitary sliding shoe into individual sections or portions has a negative effect on the pressing force distribution transverse to the direction of running of the web and leads to deficiencies in quality of the respectively processed product.